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The central pathological link in addictive states is the drug withdrawal syndrome. Usually, severe manifestations of the withdrawal syndrome are associated with reduced sensitivity of postsynaptic receptors (desensitization), lower density of receptors and impaired transport of neurotransmitters, and the rebound effect. Zebrafish is an effective tool in the study of classic withdrawal symptoms and special cases of withdrawal of other selected psychoactive drugs.

The zebrafish tail immobilization test is a relatively new method for analyzing zebrafish behavior, based on the paradigm of learned helplessness, when the animal is exposed to an uncontrollable stressor, and soon abandons all attempts to avoid the aversive stimulus, adopting a posture of immobility. As an aversive stimulus acts restraining fish tail in a viscose sponge, without restricting the mobility of the lateral fins and the front of the body. The zebrafish tail immobilization test is suitable for detecting depressive-like despair behavior in zebrafish, paralleling clinical apathy and lethargy in depression.

Anxiety is a complex and multifaceted neurobehavioral disorder that includes various forms of chronic pathological anxiety and fears, and is also the cause for various comorbid pathologies, such as depression or cardiovascular diseases. Behavioral testing of various model organisms, including the zebrafish (Danio rerio), is widely used to study neurobiological mechanisms of anxiety. Here, we discuss the novel tank test, the open field test, light-dark box and shoaling test that are widely used in translational biological psychiatry to characterize anxiety-related behavioral phenotypes in zebrafish.

T- and Y-shaped mazes are traditionally used to assess spatial learning and memory of zebrafish. In the installation of the T-shaped maze, the fish are taught to swim into the desired sleeve and not swim into the wrong one using both positive (for example, food reinforcement) and negative (for example, electric current) stimuli to form more persistent reflexes. The Y-shaped maze is based on the principle of spontaneous choice. Spontaneous choice behavior describes the tendency of animals to change their direction of rotation in a series of successive turns. Each choice statistically depends on the previous one, which indicates its mnestic origin. Unlike other types of memory tasks, testing in the Y-shaped maze does not require prior training or reinforcement (as in the T-shaped maze). Both aquatic mazes are becoming useful tools for assessing zebrafish cognitive phenotypes.

Social interactions between conspecifics are an important factor in normal development of an individual in a community, and their deficits correlate with multiple psychiatric disorders. Several methods for assessing social behavior and its deficits have been described for zebrafish (Danio rerio), and include tests for social preference and social interaction. These tests are commonly used to model a wide range of social phenotypes that are potentially relevant to studying depression, pathological aggression, schizophrenia, autism, and other brain diseases. An important and widely used method for determining social behavior is the shoaling test, based on the innate, genetically fixed feature of zebrafish to form shoals/schools, the density of which depends on many factors, such as the presence of a predator, the effect of pharmacological drugs, etc. Aggression, along with shoaling, is an important manifestation of social behavior, which is also a core symptoms of multiple brain diseases, such as control disorder and conduct disorder. Here, we discuss various methods for assessing aggressive behavior in zebrafish (e.g., the mirror reflection tests), and their shoaling agonistic behaviors.

Depression is a widespread, severely debilitating mental disorder characterized by low mood, anhedonia, fatigue, decreased attention, suicidality and psychomotor retardation, accompanied by neuroendocrine and molecular disorders. Zebrafish have neuroendocrine and neurotransmitter systems similar to humans, as well as high genetic homology, and are rapidly becoming popular model organisms for modeling depressive-like conditions. Here, we discuss modern behavioral, pharmacological and genetic models of depression in zebrafish, their methodological applications and translational implications.

Epilepsy is a common neurological disease that has many causes with unclear pathophysiological mechanisms. Epilepsy, commonly studied in rodents, can also be modeled in zebrafish (Danio rerio). There are effective pharmacological and genetic models for zebrafish, sensitive to both pro and anticonvulsant effects. These aquatic models are likely to help expand the fundamental knowledge about the mechanisms of epilepsy pathogenesis and develop epilepsy therapy.

Delirium is an acute psychiatric syndrome characterized by impaired attention, perception and orientation in space. Albeit known for millennia, the mechanisms and risk factors of delirium remain poorly understood. Experimental animal models, especially rodents, become widely used to understand these pathogenetic aspects. However, a new model organism zebrafish (Danio rerio) also has promise in this field. Discussed here, recent behavioral tests and protocols for zebrafish enable assessing their behavioral and cognitive function, and its experimental modulation by deliriant drugs and other factors.

Environmental novelty is one of the most potent stressors in animals and is often used in behavioral neuroscience to study affective and cognitive impairments. However, in the process of studying an unfamiliar environment in experimental animals, there is a decrease in stress due to habituation (adaptation, habituation). In various behavioral tests in zebrafish, this manifests as swimming in areas that pose a potential danger to them: the upper part of the aquarium in the novel tank test and the central part in the open field test. When building an effective survival strategy, it is important to navigate in an unfamiliar environment from a home base the safest area that serves as a starting point in exploring a novel arena. Both discussed here, habitation and establishing the home base, are important for assessing cognitive behavioral traits in zebrafish related to short-term spatial working memory.

Background: Cognitive deficits represent an urgent biomedical problem, and are commonly reduced by nootropic drugs. Animal models, including both rodents and zebrafish, offer a valuable tool for studying cognitive phenotypes and screening novel nootropics. Beta-alanine and its derivatives have recently been proposed to exert nootropic activity. Aims: This study aimed to characterize putative nootropic profile of a novel β-alanine analogue, 1,3-diaminopropane (MB-005), in adult zebrafish. Methods: Nootropic profile of MB-005 was assessed in adult zebrafish in the novel tank and conditioned place aversion (CPA) tests acutely, and in cued-learning plus-maze (PMT) tests chronically. Results/Outcomes: MB-005 did not alter zebrafish anxiety-like behavior or monoamine neurochemistry acutely, improved short-term memory in the CPA test, but impaired cognitive performance in both CPA and PMT tests chronically. Conclusions/Interpretation: This study reveals high sensitivity of zebrafish cognitive phenotypes to MB-005, suggesting it as a potential novel cognitive enhancer acutely, but raises concerns over its cognitive (and, possibly, other) side-effects chronically.

Mood disorders, especially depression, are a major cause of human disability. The loss of pleasure (anhedonia) is a common, severely debilitating symptom of clinical depression. Experimental animal models are widely used to better understand depression pathogenesis and to develop novel antidepressant therapies. In rodents, various experimental models of anhedonia have already been developed and extensively validated. Complementing rodent studies, the zebrafish (Danio rerio) is emerging as a powerful model organism to assess pathobiological mechanisms of affective disorders, including depression. Here, we critically discuss the potential of zebrafish for modeling anhedonia and studying its molecular mechanisms and translational implications.

Long-term recurrent stress is a common cause of neuropsychiatric disorders. Animal models are widely used to study the pathogenesis of stress-related psychiatric disorders. The zebrafish (Danio rerio) is emerging as a powerful tool to study chronic stress and its mechanisms. Here, we developed a prolonged 11-week chronic unpredictable stress (PCUS) model in zebrafish to more fully mimic chronic stress in human populations. We also examined behavioral and neurochemical alterations in zebrafish, and attempted to modulate these states by 3-week treatment with an antidepressant fluoxetine, a neuroprotective omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA), a pro-inflammatory endotoxin lipopolysaccharide (LPS), and their combinations. Overall, PCUS induced severe anxiety and elevated norepinephrine levels, whereas fluoxetine (alone or combined with other agents) corrected most of these behavioral deficits. While EPA and LPS alone had little effects on the zebrafish PCUS-induced anxiety behavior, both fluoxetine (alone or in combination) and EPA restored norepinephrine levels, whereas LPS + EPA increased dopamine levels. As these data support the validity of PCUS as an effective tool to study stress-related pathologies in zebrafish, further research is needed into the ability of various conventional and novel treatments to modulate behavioral and neurochemical biomarkers of chronic stress in this model organism. © 2021, The Author(s). This research was supported solely by the Russian Science Foundation (RSF) grant 19‐15‐00053. K.A.D. is supported by the Special Rector’s Productivity Fellowship for SPSU PhD Students, and the lab is supported by St. Petersburg State University state budgetary funds (project ID 73026081). A.V.K. is the Chair of the International Zebrafish Neuroscience Research Consortium (ZNRC) and President of the International Stress and Behavior Society (ISBS, www.stress-and-behavior.com) that coordinated this collaborative multi-laboratory project. The consortium provided a collaborative idea exchange platform for this study, it is not considered as affiliation and did not fund the study. A.V.K. lab is supported by the Southwest University (SWU) Zebrafish Platform Construction Fund (Chongqing, China). The authors thank Professor Raul R. Gainetdinov (Institute of Translational Biomedicine, St. Petersburg State University, St. Petersburg, Russia) for his generous assistance with the HPLC studies in his laboratory. The funders had no role in the design, analyses, and interpretation of the submitted study, or decision to publish.

Depression is a widespread and severely debilitating neuropsychiatric disorder whose key clinical symptoms include low mood, anhedonia and despair (the inability or unwillingness to overcome stressors). Experimental animal models are widely used to improve our mechanistic understanding of depression pathogenesis, and to develop novel antidepressant therapies. In rodents, various experimental models of 'behavioral despair' have already been developed and rigorously validated. Complementing rodent studies, the zebrafish (Danio rerio) is emerging as a powerful model organism to assess pathobiological mechanisms of depression and other related affective disorders. Here, we critically discuss the developing potential and important translational implications of zebrafish models for studying despair and its mechanisms, and the utility of such aquatic models for antidepressant drug screening.

Depression and schizophrenia are two highly prevalent and severely debilitating neuropsychiatric disorders. Both conventional antidepressant and antipsychotic pharmacotherapies are often inefficient clinically, causing multiple side effects and serious patient compliance problems. Collectively, this calls for the development of novel drug targets for treating depressed and schizophrenic patients. Here, we discuss recent translational advances, research tools and approaches, aiming to facilitate innovative drug discovery in this field. Providing a comprehensive overview of current antidepressants and antipsychotic drugs, we also outline potential novel molecular targets for treating depression and schizophrenia. We also critically evaluate multiple translational challenges and summarize various open questions, in order to foster further integrative cross-discipline research into antidepressant and antipsychotic drug development.

Background: The dopamine transporter (DAT) is the main regulator of dopamine concentration in the extrasynaptic space. The pharmacological inhibition of the DAT results in a wide spectrum of behavioral manifestations, which have been identified so far in a limited number of species, mostly in rodents. Aim: Here, we used another well-recognized model organism, the zebrafish ( Danio rerio), to explore the behavioral effects of GBR 12909, a highly-affine selective DAT blocker. Methods: We evaluated zebrafish locomotion, novelty-related exploration, spatial cognition, and social phenotypes in the novel tank, habituation and shoaling tests, following acute 20-min water immersion in GBR 12909. Results: Our findings show hypolocomotion, anxiety-like state, and impaired spatial cognition in fish acutely treated with GBR 12909. This behavioral profile generally parallels that of the DAT knockout rodents and zebrafish, and it overlaps with behavioral effects of other DAT-inhibiting drugs of abuse, such as cocaine and D-amphetamine. Conclusion: Collectively, our data support the utility of zebrafish in translational studies on DAT targeting neuropharmacology and strongly implicate DAT aberration as an important mechanisms involved in neurological and psychiatric diseases.

3,4-Dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide (U-47700) is a selective μ–opioid receptor agonist originally synthesized as a prospective analgesic drug. Several times more potent than morphine, U-47700 has high abuse potential and may cause clinical neurotoxicity, euphoria, respiratory depression and occasional mortality. U-47700 also evokes analgesia, sedation and euphoria-like states in both humans and rodents. Despite the growing use and abuse of U-47700, its psychopharmacological and toxicological profiles in vivo remain poorly understood. The zebrafish (Danio rerio) is rapidly becoming a popular aquatic model organism for central nervous system (CNS) disease modeling and drug discovery. Here, we examine acute (1, 5, 10, 25 and 50 mg/L for 20-min) and chronic (0.1, 0.5 and 1 mg/L for 14 days) effects of U-47700 in adult zebrafish. Overall, we found overt sedation evoked in fish by acute, and hyperlocomotion with an anxiolytic-like action by chronic, drug treatments. Acute treatment with 1 and 10 mg/L U-47700 also resulted in detectable amounts of this drug in the brain samples, supporting its permeability through the blood-brain barrier. Collectively, these findings emphasize complex dose- and treatment-dependent CNS effects of U-47700 following its acute and chronic administration. Our study also supports high sensitivity of zebrafish to U-47700, and suggests these aquatic models as promising in-vivo screens for probing potential CNS effects evoked by novel synthetic opioid drugs.

Neuroglia, including microglia and astrocytes, is a critical component of the central nervous system (CNS) that interacts with neurons to modulate brain activity, development, metabolism and signaling pathways. Thus, a better understanding of the role of neuroglia in the brain is critical. Complementing clinical and rodent data, the zebrafish (Danio rerio) is rapidly becoming an important model organism to probe the role of neuroglia in brain disorders. With high genetic and physiological similarity to humans and rodents, zebrafish possess some common (shared), as well as some specific molecular biomarkers and features of neuroglia development and functioning. Studying these common and zebrafish-specific aspects of neuroglia may generate important insights into key brain mechanisms, including neurodevelopmental, neurodegenerative, neuroregenerative and neurological processes. Here, we discuss the biology of neuroglia in humans, rodents and fish, its role in various CNS functions, and further directions of translational research into the role of neuroglia in CNS disorders using zebrafish models.

Hallucinogenic drugs potently affect brain and behavior and have also recently emerged as potentially promising agents in pharmacotherapy. Complementing laboratory rodents, the zebrafish (

Neurodevelopmental disorders (NDDs) caused by aberrant brain growth and development are life-long, debilitating illnesses that markedly impair the quality of life. Animal models are a valuable tool for studying NDD pathobiology and therapies. Mounting evidence suggests the zebrafish (Danio rerio) as a useful model organism to study NDDs, possessing both high physiological homology to humans and sensitivity to pharmacological and genetic manipulations. Here, we summarize experimental models of NDDs in zebrafish and highlight the growing translational significance of zebrafish NDD-related phenotypes. We also emphasize the need in further development of zebrafish models of NDDs to improve our understanding of their pathogenesis and therapeutic treatments.

Genetic mutations in FUS, a DNA/RNA-binding protein, are associated with inherited forms of frontotemporal lobar degeneration (FTLD) and amyotrophic lateral sclerosis (ALS). A novel transgenic FUS[1-359]-tg mouse line recapitulates core hallmarks of human ALS in the spinal cord, including neuroinflammation and neurodegeneration, ensuing muscle atrophy and paralysis, as well as brain pathomorphological signs of FTLD. However, a question whether FUS[1-359]-tg mouse displays behavioural and brain pro-inflammatory changes characteristic for the FTLD syndrome was not addressed. Here, we studied emotional, social and cognitive behaviours, brain markers of inflammation and plasticity of pre-symptomatic FUS[1-359]-tg male mice, a potential FTLD model. These animals displayed aberrant behaviours and altered brain expression of inflammatory markers and related pathways that are reminiscent to the FTLD-like syndrome. FTLD-related behavioural and molecular Journal of Cellular and Molecular Medicine features were studied in the pre-symptomatic FUS[1-359]-tg mice that received standard or new ALS treatments, which have been reported to counteract the ALS-like syndrome in the mutants. We used anti-ALS drug riluzole (8 mg/kg/d), or anti-inflammatory drug, a selective blocker of cyclooxygenase-2 (celecoxib, 30 mg/kg/d) for 3 weeks, or a single intracerebroventricular (i.c.v.) infusion of human stem cells (Neuro-Cells, 500 000-CD34+), which showed anti-inflammatory properties. Signs of elevated anxiety, depressive-like behaviour, cognitive deficits and abnormal social behaviour were less marked in FUS-tg–treated animals. Applied treatments have normalized protein expression of interleukin-1β (IL-1β) in the prefrontal cortex and the hippocampus, and of Iba-1 and GSK-3β in the hippocampus. Thus, the pre-symptomatic FUS[1-359]-tg mice demonstrate FTLD-like abnormalities that are attenuated by standard and new ALS treatments, including Neuro-Cell preparation. © 2020 The Authors. Journal of Cellular and Molecular Medicine published by Foundation for Cellular and Molecular Medicine and John Wiley & Sons Ltd We thank Thomas Ricker and Alexander Trofimov for their valuable technical contribution, RSF-18-15-00357 and Neuroplast-BV (Maastricht, Netherlands) for a supply of FUS[1-359]-tg mice and ?Neuro-Cells', respectively, RFBR-18-015-00450 for a help with in vitro work and ?5-100' Russian Excellence Program for a support.

Background: The contribution of gene-environment interactions that lead to excessive aggression is poorly understood. Environmental stressors and mutations of the gene encoding tryptophan hydroxylase-2 (TPH2) are known to influence aggression. For example, TPH2 null mutant mice (Tph2−/−) are naturally highly aggressive, while heterozygous mice (Tph2+/−) lack a behavioral phenotype and are considered endophenotypically normal. Here we sought to discover whether an environmental stressor would affect the phenotype of the genetically ‘susceptible’ heterozygous mice (Tph2+/−). Methods: Tph2+/− male mice or Tph2+/+ controls were subjected to a five-day long rat exposure stress paradigm. Brain serotonin metabolism and the expression of selected genes encoding serotonin receptors, AMPA receptors, and stress markers were studied. Results: Stressed Tph2+/− mice displayed increased levels of aggression and social dominance, whereas Tph2+/+ animals became less aggressive and less dominant. Brain tissue concentrations of serotonin, its precursor hydroxytryptophan and its metabolite 5-hydroxyindoleacetic acid were significantly altered in all groups in the prefrontal cortex, striatum, amygdala, hippocampus and dorsal raphe after stress. Compared to non-stressed animals, the concentration of 5-hydroxytryptophan was elevated in the amygdala though decreased in the other brain structures. The overexpression of the AMPA receptor subunit, GluA2, and downregulation of 5-HT6 receptor, as well as overexpression of c-fos and glycogen-synthase-kinase-3β (GSK3-β), were found in most structures of the stressed Tph2+/− mice. Limitations: Rescue experiments would help to verify causal relationships of reported changes. Conclusions: The interaction of a partial TPH2 gene deficit with stress results in pathological aggression and molecular changes, and suggests that the presence of genetic susceptibility can augment aggression in seemingly resistant phenotypes. © 2020 The Authors 602805 Seventh Framework Programme, FP7 Deutsche Forschungsgemeinschaft, DFG: CRC TRR 58 A1/A5 Horizon 2020 Framework Programme, H2020: 728018 Russian Foundation for Basic Research, RFBR: 15-04-03602 Deutsche Forschungsgemeinschaft, DFG Russian Foundation for Basic Research, RFBR The authors’ work reported here was supported Deutsche Forschungsgemeinschaft (DFG: CRC TRR 58 A1/A5), the European Union's Seventh Framework Programme (FP7/2007–2013) under Grant No. 602805 (Aggressotype) and the Horizon 2020 Research and Innovation Programme under Grant No. 728018 (Eat2beNICE) (to KPL and TS), the “5-100” Russian Academic Excellence Project (to KPL and TS) and the Russian Foundation of Basic Research (RFBR Grant No. 15-04-03602 to TS). We appreciate the valuable technical help of Dr. Joao Costa-Nunes and Dolores Bonopartos with this project.

Aims: Mutations in DNA/RNA-binding factor (fused-in-sarcoma) FUS and superoxide dismutase-1 (SOD-1) cause amyotrophic lateral sclerosis (ALS). They were reproduced in SOD-1-G93A (SOD-1) and new FUS[1-359]-transgenic (FUS-tg) mice, where inflammation contributes to disease progression. The effects of standard disease therapy and anti-inflammatory treatments were investigated using these mutants. Methods: FUS-tg mice or controls received either vehicle, or standard ALS treatment riluzole (8 mg/kg/day), or anti-inflammatory drug a selective blocker of cyclooxygenase-2 celecoxib (30 mg/kg/day) for six weeks, or a single intracerebroventricular (i.c.v.) infusion of Neuro-Cells (a preparation of 1.39 × 106 mesenchymal and hemopoietic human stem cells, containing 5 × 105 of CD34+ cells), which showed anti-inflammatory properties. SOD-1 mice received i.c.v.-administration of Neuro-Cells or vehicle. Results: All FUS-tg-treated animals displayed less marked reductions in weight gain, food/water intake, and motor deficits than FUS-tg-vehicle-treated mice. Neuro-Cell-treated mutants had reduced muscle atrophy and lumbar motor neuron degeneration. This group but not celecoxib-FUS-tg-treated mice had ameliorated motor performance and lumbar expression of microglial activation marker, ionized calcium-binding adapter molecule-1 (Iba-1), and glycogen-synthase-kinase-3ß (GSK-3ß). The Neuro-Cells-treated-SOD-1 mice showed better motor functions than vehicle-treated-SOD-1 group. Conclusion: The neuropathology in FUS-tg mice is sensitive to standard ALS treatments and Neuro-Cells infusion. The latter improves motor outcomes in two ALS models possibly by suppressing microglial activation. © 2019 The Authors. CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd We thank ?5-100? Russian Excellence Program, Prof. Daniel C. Anthony, Diana Babayevskaya, and Arina Kosakova for their highly valuable contribution. ?Neuro-Cells? preparation was provided by Neuroplast BV, Maastricht, Netherlands.

Multiple species display robust behavioral variance among individuals due to different genetic, genomic, epigenetic, neuroplasticity and environmental factors. Behavioral individuality has been extensively studied in various animal models, including rodents and other mammals. Fish, such as zebrafish (Danio rerio), have recently emerged as powerful aquatic model organisms with overt individual differences in behavioral, nociceptive and other CNS traits. Here, we evaluate individual behavioral differences in mammals and fish, emphasizing the importance of cross-species analyses of intraspecies variance in experimental models of normal and pathological CNS functions.

Kava (kava kava, Piper methysticum) is a common drug-containing plant in the Pacific islands. Kavalactones, its psychoactive compounds, exert potent central nervous system (CNS) action clinically and in animal models. However, the exact pharmacological profiles and mechanisms of action of kava on the brain and behavior remain poorly understood. Here, we discuss clinical and experimental data on kava psychopharmacology and summarize chemistry and synthesis of kavalactones. We also review its societal impact, drug use and abuse potential, and future perspectives on translational kava research.

Serotonergic hallucinogenic drugs potently affect human brain and behavior, and have recently emerged as potentially promising agents in psychopharmacotherapy. Complementing rodent studies, zebrafish (Danio rerio) is a powerful animal model for screening neuroactive drugs, including serotonergic agents. Here, we test ten different N-Benzyl-2-phenylethylamine (NBPEA) derivatives with the 2,4- and 3,4-dimethoxy substitutions in the phenethylamine moiety and the - OCH3, -OCF3, -F, -Cl and -Br substitutions in theorthoposition of phenyl ring ofN-benzyl fragment, assessing their behavioral and neurochemical effects in adult zebrafish. Overall, substitutions inN-benzyl fragment primarily affected zebrafish locomotion, and in phenethylamine moiety - anxiety-like behavior, also modulating brain serotonin and/or dopamine turnover. We also identified several behavioral clusters, including anxiogenic/hypolocomotor (24H-NBF, 24H-NBOMe and 34H-NBF), behaviorally inert (34H-NBBr, 34H-NBCl and 34H- NBOMe), anxiogenic/hallucinogenic-like (24H-NBBr, 24H-NBCl and 24H-NBOMe(F)), and anxiolytic/hallucinogenic-like (34H-NBOMe(F)) agents. The 24H-NBOMe(F) and 34H-NBOMe(F) also reduced despair-like behavior in zebrafish. The artificial intelligence-driven phenotyping supports association of multiple compounds with NMDA antagonists and/or MDMA, supporting their potential hallucinogenic-like properties, as well as other valuable psychoactive effects.In silicofunctional molecular activity modelling also supports existing of similarities between studied NBPEAs drugs, MDMA, and ketamine. Functional analysis implicates potential involvement of serotonin release stimulating activity, calcium channel (voltage-sensitive) activity, some serotonin receptors activity and variety of psychiatric and neurologic disorders treatments activities. Overall, we report potent neuroactive properties of several novel syntheticN-benzylphenylethylamines in anin vivovertebrate model system (zebrafish), raising the possibility of their potential use in clinical practice.

Zebrafish (Danio rerio) are rapidly emerging in biomedicine as promising tools for disease modelling and drug discovery. The use of zebrafish for neuroscience research is also growing rapidly, necessitating novel reliable and unbiased methods of neurophenotypic data collection and analyses. Here, we applied the artificial intelligence (AI) neural network-based algorithms to a large dataset of adult zebrafish locomotor tracks collected previously in a series of in vivo experiments with multiple established psychotropic drugs. We first trained AI to recognize various drugs from a wide range of psychotropic agents tested, and then confirmed prediction accuracy of trained AI by comparing several agents with known similar behavioral and pharmacological profiles. Presenting a framework for innovative neurophenotyping, this proof-of-concept study aims to improve AI-driven movement pattern classification in zebrafish, thereby fostering drug discovery and development utilizing this key model organism.

Epilepsy is a highly prevalent, severely debilitating neurological disorder characterized by seizures and neuronal hyperactivity due to an imbalanced neurotransmission. As genetic factors play a key role in epilepsy and its treatment, various genetic and genomic technologies continue to dissect the genetic causes of this disorder. However, the exact pathogenesis of epilepsy is not fully understood, necessitating further translational studies of this condition. Here, we applied a computational in silico approach to generate a comprehensive network of molecular pathways involved in epilepsy, based on known human candidate epilepsy genes and their established molecular interactors. Clustering the resulting network identified potential key interactors that may contribute to the development of epilepsy, and revealed functional molecular pathways associated with this disorder, including those related to neuronal hyperactivity, cytoskeletal and mitochondrial function, and metabolism. While traditional antiepileptic drugs often target single mechanisms associated with epilepsy, recent studies suggest targeting downstream pathways as an alternative efficient strategy. However, many potential downstream pathways have not yet been considered as promising targets for antiepileptic treatment. Our study calls for further research into the complexity of molecular mechanisms underlying epilepsy, aiming to develop more effective treatments targeting novel putative downstream pathways of this disorder.

Psychiatric disorders are highly prevalent brain pathologies that represent an urgent, unmet biomedical problem. Since reliable clinical diagnoses are essential for the treatment of psychiatric disorders, their animal models with robust, relevant behavioral and physiological endpoints become necessary. Zebrafish (Danio rerio) display well-defined, complex behaviors in major neurobehavioral domains which are evolutionarily conserved and strikingly parallel to those seen in rodents and humans. Although zebrafish are increasingly often used to model psychiatric disorders, there are also multiple challenges with such models as well. The field may therefore benefit from a balanced, disease-oriented discussion that considers the clinical prevalence, the pathological complexity, and societal importance of the disorders in question, and the extent of its detalization in zebrafish central nervous system (CNS) studies. Here, we critically discuss the use of zebrafish for modeling human psychiatric disorders in general, and highlight the topics for further in-depth consideration, in order to foster and (re)focus translational biological neuroscience research utilizing zebrafish. Recent developments in molecular biology research utilizing this model species have also been summarized here, collectively calling for a wider use of zebrafish in translational CNS disease modeling.